Sensor calibration on CO2 monitoring: Which statement is most accurate?

• A. Calibration eliminates all measurement errors.
• B. Calibration can introduce errors, typically ±50 ppm at rated temperature.
• C. Calibration doubles the outdoor air requirement.
• D. Calibration reduces sensor life.

Answer: (B)

Calibration improves accuracy by aligning the sensor output with a known CO2 concentration, but it does not remove every measurement error. After calibration, residual uncertainty remains because of factors like the reference gas accuracy, sensor nonlinearity, temperature and humidity effects, aging, and measurement noise. Saying that the residual error is typically about ±50 ppm at rated temperature captures how calibration can still introduce small, but real, uncertainty even under specified conditions. In practice, this means calibration helps a lot, but it doesn’t make the sensor perfect; you’ll still have some error bounds to account for in monitoring and control.

The other statements overstate or misstate what calibration does: it does not eliminate all errors, it does not automatically change outdoor air requirements, and it does not inherently shorten sensor life.